1. Field of Invention
This invention relates to an oiling roller for a drum maintenance unit.
2. Description of Related Art
It is known to utilize intermediate transfer layers in ink printing systems, such as disclosed in U.S. Pat. Nos. 6,068,372 and 6,431,703 to Rousseau et al. These systems utilize an oiling roller that engages the imaging drum and applies a liquid intermediate transfer layer to the imaging drum. The print head ejects drops of ink onto the liquid intermediate transfer layer to form an ink image thereon. A receiving substrate such as paper is then brought into contact with the intermediate transfer layer on the imaging drum and the ink image is transferred to the receiving substrate.
U.S. Pat. No. 6,480,694 or Kimura et at. describes an oiling roller made of a hollow cylindrical porous formed body that retains the release agent lubricant in the microdiameter voids and pores inside. The lubricant moves throughout the roller body by capillary force. The amount of lubricant applied to the imaging drum can be controlled by the amount of permeability resistance in the porous material. The retaining pores also prevent leakage of the lubricant.
A part of the solid ink technology printing process includes the drum maintenance unit. One of the drum maintenance unit's objectives is to apply a metered amount of release agent onto to the imaging drum prior to the print head imaging process. A metering blade meters the release agent applied by the oiling roller into a very thin film on the imaging drum that will be sufficient to have the ink preferably stick to the media rather than to the drum. Proper imaging requires release agent layer uniformity. When the agent is not applied uniformly the images exhibit noticeable streaks. The release agent can also change the gloss of images on a substrate and the projection efficiency of transparencies.